In image forming devices utilizing an electrophotographic system such as copying machines, fax machines and printers, a variety of roller members (e.g., charging rollers, transfer rollers, toner supply rollers, developing rollers, cleaning rollers, paper-feeding rollers, and pressure rollers for fixation) are used. These roller members generally have a basic structure in which an elastic layer composed of a rubber material or a resin material is supported on the outer circumference of a shaft (core metal).
Depending on the intended use of the roller members, in order to satisfy the required performance, a surface layer is further arranged on the elastic layer to control the roller surface properties. For such a surface layer, conventionally, a flexible material is used so as to suppress cracking and abrasion of the layer itself and, particularly, in charging rollers and developing rollers, in order to adjust the surface roughness for the purposes of, for example, controlling the charging properties, particles are dispersed in the surface layer in some cases. For instance, Patent Document 1 discloses a conductive roller comprising: a shaft; an elastic layer formed on the outer circumference of the shaft; and a resin coating layer formed on the peripheral surface of the elastic layer, wherein the resin coating layer has a glass transition temperature (Tg) of 40° C. or higher and a friction coefficient of 0.5 or less, and it is also disclosed therein that fine particles are incorporated into the resin coating layer.